Importance Low-dose computed tomography (CT) screening was shown to reduce lung cancer–specific mortality in a large randomized trial of a high-risk population. The decision to pursue CT screening for lung cancer is a timely question raised by individuals at risk of lung cancer and by their health care practitioners.

Objectives To discuss the evidence for use of chest x-rays and low-dose CT in screening for lung cancer; to describe potential benefits, harms, and uncertainties of CT screening; and to review current guidelines for CT screening.

Evidence Review MEDLINE and the Cochrane Library were searched from 1984 to 2012. Additional citations were obtained from lists of references from select research and review articles on this topic. Evidence was graded using the American Hospital Association level of evidence guidelines.

Findings Low-dose CT screening has been associated with a 20% reduction in lung cancer mortality in a large randomized controlled trial (National Lung Screening Trial [NLST]) of a high-risk population. Mortality data have not yet been reported for 5 other randomized controlled trials, and the sample sizes were too small to detect a meaningful difference in 2 other completed trials. A major risk of CT screening is a high false-positive rate, with associated risks and costs associated with follow-up CT scans and the potential for more invasive diagnostic procedures. Published guidelines for screening indicate a consensus that screening may be indicated for individuals who meet entry criteria for the NLST, but some guidelines expand their recommendations for screening beyond these criteria.

Conclusions and Relevance Individuals at high risk of lung cancer who meet the criteria for CT screening in published guidelines should participate in an informed and shared decision-making process by discussing the potential benefits, harms, and uncertainties of screening with their physicians.